Process of treating interpolymers of styrene, allylic fumarate, and allylic alcohol



at... Fears, 1949 2,461,735

; raoorzss F TREATING iN'rEnroLYMERs or STYRENE, ALLYLIC FUMARATE, AND

ALLYLIC ALCOHOL Charles A. Heiberger, Nitro, W. Va., asslgnor to UnitedStates Rubber Company, New York, N. Y., a corporation of New ersey NoDrawing. Application December 10, 1946.

Serial No. 715,345

7 Claims. (Cl. 260-485) This invention relates to improvements insoluble interpolymers of styrene, allylic fumarate, and allylic alcohol.

In Tawney application Serial No. 580,487,

at a sumcienty high temperature to dissociate from the interpolymer, bylactonization or other pyrolytic reaction, an allylic alcohol, and con-3 currently with the heating, the liberated allylic filed March 1, 1945,and now abandoned, ref- 5 alcohol is removed either continuously orintererence is made to interpolymerlzing a, mixture mittently from theheating (reaction) zone conof styrene, a monomeric allylic fumarate, anda taining t e r n- T e p r ion is ontinued monomeric allylic alcohol toform therefrom a until the residue, 1. e., the th y fi d soluble fusibleinterpolymerizate. The products int rpolymer, con in upon standin for 7days are generally colorless solids. Elementary 10 at 70 0., not morethan 0.4% by wei of ee analysis and other specific tests indicate thatally a o l b ed on the solid resin. The rethe products are ternaryinterpolymers. Typical moval of the liberated allylic alcohol from theproducts may contain, for example, about 50% interp lymerreaction zoneduring the heatin is by weight of diallyl fumarate. about 25% byrequired inorderito bring the lactonization, or weight of styrene. andabout 25% by weight of other reaction. to substantial completion. allylalcohol. They contain. attached to the As the examples of my invent ongiven below polymer chain, hydroxymethyl groups derived will show, theallylic alcohol which causes the from the interpolymerized allylicalcohol moleobjectionable lachrymatory efiects under ordicules, whichrenders the copolymers capable of nary condi ions of commercial use isnot mere modification by agents reactive w th primary unreacted allylical ohol remaining in the interalcohols. e. g., alkyl haldes. organicacids, etc. polym rs after preparat on. Through ordinary The productscontain residual unsaturation, and methods the interpolymers can becarefully application of heat, particularly in the presence purifi d yreprecini ation fro or nic lv n of catalysts, induces furtherpolymerization to or bv adding an entrainer'and distilling to remove theinsoluble, infusible stage. The unsaturated volatile impurit es, yet theresulting purified products are soluble in many organic solvents,interpolvmers will be free from lachrymatory e. g., acetone, xylene,etc. It has now been pro erties for only a very short period of t me.found that the resulting soluble ternary inter- After a few days ofstorage even the carefully polymers. under stora e conditions and use.propurified interpolymers will develop lachrymatory duce undesirablelachrymatory effects induced properties that render them objectionablefor by liberation of allylic alcohol. The mechan sm commercial use. bywhich these interpolymers liberate allylic My invention, therefore. isdirected towards a alcohol is not definitely known. but it is believedthermal'metl od of modifying the interpolymers that it takes placethrough formation of lactone to liberate and remove combined allylicalcohol rings in the polymer molecules. which otherwise would beliberated slowly during It is an object of this invention to so treatstorage. This method requires a substantially the preformed solubleinterpolymers so as to longer time and/or higher temperature than isreduce to a minimum the tendency of the interemployed in ordinaryremoval of unreacted polymers to produce such undesirable effects. Aallylic alcohol from the crude interpolymers befurther object resides inthermally modifying the 40 cause t e lactonization or other pyrolyticdesaid preformed interpolymers whereby. through composition by whichcombined allylic alcohol lactonization or other pyrolytic reaction, theis liberated takes place relatively slowly. Thus, thermally modifiedinterpolymers show, after the small amount of such reaction which may rlittle or no tendency to produce la h ytake place incidental to ordinaryremoval, by fl 'y ts- Ot Objects W l be appare t low-temperaturedistillation, of unreacted refrom the following description. actants,does not serve to make the resultant According to the invention, thepreformed interpolymers usable commercially because fursolublestyrene-allylic fumarate-allylic alcohol ther lactonization takes placeduring storage and interpolymer which shows undesirable lachrytheinterpolymers thereby become lachrymatory. matory eflects on storage,mixing, etc., is heated My invention contemplates bringing the reactionliberating allylic alcohol to substantial completion by materiallyprolonging the time for which the interpolymer is maintained at anelevated temperature, or by using substantially higher temperatures thanare required for ordinary purification by distillation.

By an allylic herein is meant the allyl and substituted allyl radicalsof the group Where X is H, methyl, or chlorine. Further, the inventionapplies not only to the use of styrene for the purpose, but to nuclearlyalkyl-substituted styrenes, e. g., p-methyl styrene, p-ethyl styrene,and to nuclearly chloro-substituted styrenes, e. g., p-chlorostyrene.

The improved soluble interpolymers are, like those of Tawney inapplication Serial No. 580,- 487, suited to the formation of tough rigidcastings and are also adapted for the preparation of cheap coatingcompositions, and have generally the same useful chemical and physicalproperties as the untreated (unheated) soluble interpolymers. They toomay be converted to insoluble and infusible products or interpolymerizedwith other unsaturated organic materials capable of additionpolymerization; particularly compounds containing an ethylenic linka e.such as methyl acrylate, allyl acrylate, allyl fumarate, vinyl acetate,etc., as described by Tawney. Similarly, they can be dissolved inappropriate solvents and used as lacquers Or as impregnating andwaterproofing compositions.

In a preferred ing of the preformed ternary acetone-soluble interpolymeris carried out in the presence of an added amount of a suitable liquidto serve both as a solvent for the resinous copolymer and as anentrainer for the allylic alcohol, sumcient in amount to make a resinsolution containing from about to about solids by weight. It is alsopreferable to add a suitable polymerization inhibitor, such as guaiacol,hydroquinone, etc., to prevent formation of gel. The resin solution isthen heated, for example, at from about C. to about C., for from about 2toIabout 6 hours, with continuous or intermittent removal, bydistillation, of the allylic alcohol formed by lactonization or otherreactions. Additional entrainer is added to the resin solution,continuously or intermittently, in order to replace that distilled offduring the treatment.

Various entrainers for the allylic alcohol may be selected. Xylene isconvenient, since it forms an azeotropic mixture with the allylicalcohol, and because it serves as a suitable solvent for the commercialuses of the polymer solution. However, other entrainers may be used,such as solvent naphtha, diacetone alcohol, carbon tetrachloride,cyclohexane, benzene, toluene, etc., the entrainer being inert towardsthe resin and having a boiling point to accommodate the temperaturerange of the heat treatment, the pressures being adjusted accordingly.If the entrainer does not form an azeotrope with the allylic alcohol,its boiling point should preferably be higher than the allylic alcoholfor efflcient removal of the latter, as will be apparent to thoseskilled in the art.

After completion of the heat treatment and entrainment of the allylicalcohol, the solids concentration may be adjusted, as desired, accordingto the requirements of the contemplated use. It will generally be foundthat in spite of the form of the invention, the heat- 4 inhibitorpresent. the heat treatment has resulted in an appreciable increase inthe viscosity,

which renders the solutions especially suitable, for instance, for usein paint spraying equipment.

The temperature of the heat treatment may vary, being preferably fromabout 90 C. to about 100 C. At temperatures much below 90 C., e. g., 70C., the reaction proceeds undesirably slowly, requiring an impracticallylong time to liberate and remove the allylic alcohol. Above 100 C.,reaction is more rapid and the tendency to form gel is increased. Agenerally useful range, however, is from 70 C. to C., the time requiredbeing generally from 1 to 24 hours.

Further, a fractionating column may be employed to advantage during theheat treatment and distillation. This enables the allylic alcohol to beremoved with a relatively small proportion of entrainer, since thelarger portion of the entrainer which is evaporated from the resinsolution is returned as reflux. In addition, the bulk of the allylicalcohol tends to become concentrated near the top of the fractionatingcolumn, keeping the concentration of allylic alcohol in the still pot ata minimum and allowing the lactonization or other reactions to proceedto substantial completion more quickly.

The following examples illustrate the invention in more detail, theparts being by weight.

EXAMPLE 1 late substantially free of allyl alcohol. Additional xylene isadded after each vacuum distillation so as to restore the concentrationof resin in the solution to about 30%.

Data for these four heating periods and distillations are given in thetable.

The total allyl alcohol'liberated during the four heating periods isthus 0.23% on the weight of solid polymer.

After the last distillation, the cooled product is dfluted to 50% solidswith xylene. One sample of this solution was stored 16 days at 70 C.,and a second sample was stored '75 days at room temperature. Thesesamples did notv liberate sufficient allyl alcohol during the storageperiods to give any objectionable lachrymatory efiect on a paint mill. y

In contrast to this example, a sample of the untreated interpolymer fromwhich ,all the unreacted allyl alcohol, originally added as such to theresinification reaction mixture, had been removed by distillation withxylene was at first satisfactory when used on the mill, but afterstorage for '7 days at 70 C. sufllcient allyl alcohol had been liberatedto render the product unsatisfactory from the standpoint of lachrymationcaused by liberated allyl alcohol.

EXAMPLE 2 In this example the heat treatment was carried outcontinuously by heating 100 parts of a 30% solution of allylalcohol-free soluble interpolymer of styrene, diallyl fumarate and allylalcohol in xylene at 95-l00 C., at a pressure of about 150 mm. ofmercury for a period of about 4.7 hours, distillation proceeding at suchrate that about 56 parts of xylene-allyl alcohol mixture distilled oifduring this time. The xylene thus removed was replaced from time to timein the still pot with fresh xylene. The resin solution was thenconcentrated to 58.6% solids by distillation. The total weight of allylalcohol liberated, as determined by bromine titration, was equal roughlyto about 0.4% Of the weight of the resin.

The resin solution was adiusted to 50% solids by the addition of xylene,and 0.5% of guaiacol inhibitor was added.

After storage for 7 days at 70 6., this heatmodified product wassufllciently free of liberated allyl alcohol to permit use on a paintmill without objectionable lachrymatory effect.

EXAMPLE 3 This illustrates the preparation of the interpolymer withoutheat treatment but with purification in the presence of xylene,according to prior practice, merely to show that the purified untreatedproduct does not have the same advantage in commercial use after a shortperiod of storage as the product treated in the manner of thisinvention.

The crude interpolymer solution, of the same monomers as in Example 1,was distilled under vacuum to remove the excess reactants, includingallyl alcohol. In the course of the distillation the vapor temperaturedropped from 55 C. at 133 mm. of mercury pressure, to 35 C. at 10 mm. ofmercury pressure. In this step 1,451 parts of distillate were removedduring a period of 2 hours. The residue was cooled and diluted with 1932parts of xylene and a second vacuum distillation was carried out toremove the residual allyl alcohol. In the course of this distillation1632 parts of xylene-allyl alcohol were removed during 4 hours, at avapor temperature ranging from 54 C. at 107 mm. pressure initially to 42C. at 30 mm. pressure at the end. I

The residue was cooled and an additional 400 parts of xylene were addedand 428 parts dstilled off during 1 hour in the same manner aspreviously. The last portion of this distillate still gave a stronglypositive test for allyl alcohol.

Another 400 parts of xylene were added to the cooled residue anddistillation was resumed for hour until 454 parts had been distilledofl, when a portion of the distillate gave a negative test for allylalcohol showing that all the free allyl alcohol in the resin solutionhad been removed.

A 50% solution of this polymer in xylene contained no lachrymator whentested shortly after the above purification, but after storage for '7days at 70 0., the polymer solution was found 6 to be stronglylachrymatory,.due to the presence of allyl alcohol liberated duringstorage.

EXAMPLE 4 A fractionating column is employed in this example. Thepurification of the crude soluble interpolymer solution, of the samemonomers as in Example 1, and the heat treatment are carried out in anessentially one-step operation.

The 1200 parts of unpurified interpolymer solution (about 25% solidresin) used in this example contained 210 parts of xylene which had beenadded to the original reaction mixture used in making the solubleinterpolymer. The solution was distilled under diminished pressure froma 2-liter flask fitted with a fractionating column 48 cm. long and 2.5cm. in diameter, packed with 6 x 6 mm. Raschig rings. About 860 parts ofxylene and allyl alcohol mixture were distilled over without reflux in1% hours. At this point the vapor temperature had risen to 65 C., at apressure of 275 mm. of mercury, and the distillate then comin overcontained less than 0.5% of allyl alcohol, indicating that removal ofunreacted allyl alcohol in the interpolymer solution was essentiallycomplete. Distillation was then continued at a high reflux ratio and ata higher temperature for another 2 hours, during which time about 209parts of xylene, containing allyl alcohol liberated by lactonization orother reactions, were removed at a vapor temperature of 73-75 C. at mm.of mercury pressure. Additional xylene was added to the resin solutionintermittently throughout the distillation so as to maintain theconcentration of resin at about 25%.

After completion of heat treatment the resin solution was concentratedto 50% solids and 0.5% guaiacol was added to inhibit prematurepolymerization. After storage for 7 days at 70 C., Y

the solution was sufiiciently free of liberated allyl alcoho1 to permituse on a paint mill without objectionable lachrymatory effect.

A convenient manner of testing the residual thermally-modifiedinterpolymer to determine the amount of free allylic alcohol, andthereby the ability or lack of ability to cause lachrymatory effects, isas follows: By free allylic alcohol is meant the allylic alcoholmeasured by the test.

A 50 mL'sample of the heat-treated resin (50% solution in, for example,-xylene solvent, with about 0.5% guaiacol added as a stabilizer) istransferred to a 250 ml. three-necked flask. The graduate is rinsed intothe flask with 50 ml. of xylene. The flask is then attached through oneneck to a. vacuum distillation apparatus equipped with a manometer andmonostat, and a Hy-vac pump. The other necks are fitted with athermometer and a capillary inlet for nitrogen. The receivers for thedistillate consist of two Dry Ice traps in series. Vacuum is applieduntil the solution boils gently and the manostat is adjusted to regulatethe pressure at this point (about 10 mm. Hg). A slow stream of nitrogenthrough the capillary inlet acts to keep the boiling smooth. By means ofa Glas-Col heating mantle, the temperature of the solution is maintainedat 20-30 C. Distillation is cont nued until about 50 ml. of distillatehave been collected.

When the distillation is complete the traps are warmed to roomtemperature, the contents combined and transferred to a separatoryfunnel in which they are extracted with two 20 ml. portions of water.The aqueou extracts, containms the aliyl alcohol, are transferred to anErlenmeyer flask to which is added suillcient concentrated sulfuric acidto make the solution 3 N in acid, and 1 drop of 0.1% methyl redsolution. The solution is then titrated slowly with 0.02 Nbromide-bromate solution to the disappearance of the red color.Extraction and titration of known solutions oi allyl alcohol in xyleneby the same procedure show constant recoveries of 92% of the allylalcohol. with this correction factor being taken into account, the titreof an unknown solution of allyl alcohol is taken as a measure or the,amount oi allyl alcohol present.

While I have shown and described various em-- bodiments oi. theinvention. it is to be understood that the invention is susceptible tothose modifications which appear within the spirit of the invention andthe scope or the appended claims.

Having thus described my invention, what I claim and desire to protectby Letters Patent is: 1. A process of improving preformed acetonesolubleinterfiolymers of a styrene, an allylic iumarate, and an allylic alcoholwhich normally exhibit lachrymatory efiects after storage, whichcomprises heating a mixture of the interpolymer and an inert liquidsolvent of the same at a temperature in the range of from '70 to 125 C.

i or from 1 to 24 hours so that the allylic alcohol is effectivelyliberated from the interpolymer, and concurrently removing from the zoneof heat treatment liberated allylic alcohol, the operations beingcontinued until the residual thermally-modified soluble interpolymershows on standing for 7 days at 70 C. the presence of not more than 0.4%weight of free allylic alcohol.

2. A process as set forth in claim 1 in which the heating is conductedconcurrently with distillation or the solvent and of liberated allylicalcohol, and said alcohol thus removed is separated from the mixeddistillate, and the inert solvent is returned as reflux to theinterpolymer solution being treated.

3. A process asset forth in claim 1 in which a gelatin inhibitor isadded to the soluble interpolymer being heat-treated. 4. A process ofimproving preformed acetonesoluble interpolymers of a styrene, anallylic fume-rate, and an ailylic alcohol which normally exhibitlachrymatory effects after storage, which comprises heating a mixture ofthe interpolymer and an inert liquid-solvent of the same at a temprature in the range of from 90 to 100 C. for

from 1 to 24 hours so that the allylic alcohol is eflectively liberatedfrom the interpolymer, and concurrently removing from the zone of heattreatment liberated allylic alcohol, the operations being continueduntil the liberation and removal of the allylic alcohol aresubstantially complete.

5. A process or improving. preformed acetonesoluble interpoiymers or astyrene, an allylic fumarate, and an aliylic alcohol which normallyexhibit lachrymatory eflects alter storage. which comprises heating amixture of the interpolymer and an inert liquid solvent 01' the'same ata temperature in the range of from 90 to 100 C. for from 1 to 24 hoursso that the allyllc alcohol is eflectively liberated from theinterpolymer, and concurrently removing irom the zone of heat treatmentliberated allylic alcohol, the operations being continued until theinterpolymer is rendered substantially non-lach ymatory when testedafter storage for seven days at C.

6. A process of improving preformed acetonesoluble interpolymers of astyrene, an allylic fumarate, 'andan allylic alcohol which normallyexhibit lachrymatory effects after storage, which comprises heating amixture of the interpolymer and an inert liquid solvent of the same at atemperature in the range of from to C. for from 1 to 24 hours so thatthe allylic alcohol is effectively liberated from the interpolymer, andconcurrently removing from the zone of heat treatment liberated allyliealcohol, the operations being continued for a sufficient time to renderthe interpolymer substantially n'onlachrymatory.

7. A process or improving preformed'acetonesoluble interpolymers ofstyrene, a diallyl iumarate, and,,allyl alcohol which normally exhibitlachrymatory effects after storage, which comprises heating a mixture ofthe interpolymer and an inert liquid solvent of the same at atemperature in the range or from 90 to 100 C. for

from 1 to 24 hours so that the allyl alcohol is effectively liberatedfrom the interpolymer, and concurrently removing from, the zone of heattreatment liberated allyl alcohol, the operations being continued for as'uflicient time to render the interpolymer substantiallynon-lachrymatory.

CHARLES A. HEIBERGER.

No references cited.

